Method for the automatic identification of sensor sensitivity

ABSTRACT

A method for the automatic identification of sensor sensitivity, according to which resistance of a specific magnitude is allocated to the sensor. The resistance is used to allocate the sensor to a specific sensor group with a predetermined sensitivity range.

[0001] The invention relates to a method for automatically detecting the sensitivity of sensors.

[0002] Sensors are currently being used in many technical fields for the purpose of detecting states, positions etc. The method described below relates chiefly to sensors that are differentiated by an individual sensitivity. It is merely preferred for the method to relate to piezoelectric sensors with the aid of which pressure, force or acceleration can be determined.

[0003] Such sensors are used, for example, in injection molds in order to determine a cavity pressure. The cavity pressure can then be used to determine, for example, the degree of filling of a cavity or the instant for the switchover from filling pressure to pressure.

[0004] A serious problem in handling such sensors resides in the individual sensor sensitivities, which are given in pC/bar (picocoulomb/bar) for pressure, or pC/N (picocouloumb/newton) for force. This sensitivity differs for each sensor for production reasons.

[0005] It is object of the present invention to develop a method of the above-named type that automatically detects the individual sensitivities of sensors and adapts the measuring ranges in a suitable device in an appropriate or optimum fashion.

[0006] This object is achieved by virtue of the fact that the sensor is assigned a resistor of a specific magnitude, by means of which the sensor is assigned to a specific sensor group with a predetermined sensitivity range.

[0007] There are, for example, three different sensor groups with three different nominal sensitivities for a specific field of application: Group 1 2.5 pC/bar Group 2  10 pC/bar Group 3  20 pC/bar

[0008] For Group 1, resistors with 100 ohm steps are used, for Group 2 resistors with 1000 ohm steps, and for Group 3 resistors with 10000 ohm steps. In this way, the groups are detected and differentiated from one another.

[0009] This is preferably followed by fine classification or delimitation within the individual groups: Group 1 2.3 pC/bar 100 ohm 2.4 pC/bar 200 ohm 2.5 pC/bar 300 ohm 2.6 pC/bar 400 ohm 2.7 pC/bar 500 ohm

[0010] Group 2  9.8 pC/bar 1000 ohm  9.9 pC/bar 2000 ohm 10.0 pC/bar 3000 ohm 10.1 pC/bar 4000 ohm 10.2 pC/bar 5000 ohm

[0011] Group 3 19.8 pC/bar 10000 ohm 19.9 pC/bar 20000 ohm 20.0 pC/bar 30000 ohm 20.1 pC/bar 40000 ohm 20.2 pC/bar 50000 ohm

[0012] The appropriate sensor that is to be used for a specific application is now preferably plugged into a charge amplifier (Plug & Play), via which the sensor sensitivity is defined. The amplifier automatically sets the optimum range.

[0013] The effectively scaled signal output for the user is communicated via control codes, and so it is superfluous for the user to input the sensitivity.

[0014] However, the aim is preferably not only to automatically detect the sensitivities in the amplifier, but also to automatically set the optimum measuring ranges. The best possible resolution of the measuring signal is always yielded in this way, and automatically. 

1. A method for automatically detecting the sensitivity of sensors, characterized in that the sensor is assigned a resistor of a specific magnitude, by means of which the sensor is assigned to a specific sensor group with a predetermined sensitivity range.
 2. The method as claimed in claim 1, characterized in that the sensor is limited within the sensor group by a specific magnitude of its resistor.
 3. The method as claimed in claim 1 or 2, characterized in that the sensor is plugged into a charge amplifier and the latter defines its sensitivity.
 4. The method as claimed in claim 3, characterized in that the optimum measuring ranges in the amplifier are also set automatically. 